YAML to JSON & JSON to YAML Converter

What it does & when you need it

You have a Kubernetes manifest, a GitHub Actions workflow, or a docker-compose file in YAML, and you need it as JSON to feed an API, a schema validator, or a piece of tooling that only speaks JSON — or the reverse, because a hand-written JSON config is painful to read and you want the terser YAML form. This converter runs both directions in your browser: it parses YAML into a data model and serializes it as JSON, or parses JSON and emits YAML. Nothing is uploaded, which matters when your config holds secrets, connection strings, or internal hostnames. When a document won't parse, you get the error message instead of a blank output, so you can see what broke.

How to use

Pick a direction with the toggle: YAML → JSON or JSON → YAML.
Paste your document into the input buffer, press Sample to load an example config, or Upload a .yaml, .yml, or .json file.
The output updates as you type. Press Copy result (or Ctrl/Cmd + Enter) to grab it. If the input is malformed, the output panel shows the parser error rather than a partial result.

Things worth knowing

JSON is (almost) a subset of YAML. As of the YAML 1.2 spec, valid JSON is also valid YAML, so pasting JSON into the YAML → JSON side usually just round-trips cleanly. The reverse is not true: YAML has multi-document streams, comments, anchors, and block scalars that have no place in the JSON grammar, so plenty of YAML cannot survive a trip through JSON unchanged. Treat JSON as the smaller, stricter target format. If you want to tidy the JSON that comes out, send it to the JSON Formatter.

Indentation is load-bearing, and tabs are illegal. YAML uses indentation to express structure the way Python does, and the spec forbids tab characters for indentation entirely — you must use spaces. A single stray tab, often pasted in from an editor that "helpfully" converts spaces, is the most common reason a YAML document refuses to parse. If you get an indentation error and the file looks right, search it for a literal tab.

Beware the Norway problem. Under YAML 1.1-style boolean rules, the bare words no, yes, on, and off (in several casings) are parsed as booleans. That means a country-code list containing NO for Norway can silently become false, and a version: on field becomes true. The fix is to quote any scalar that could be mistaken for a boolean, number, or null — "NO", "on", "1.20" — which forces it to stay a string. When you convert to JSON and see false where you expected a code, this is almost always why.

Converting to JSON is lossy by design. YAML comments introduced with # carry no data, so they disappear the moment you serialize to JSON — JSON has no comment syntax at all. Likewise, anchors and aliases (&name to define, *name to reference) are a YAML feature for reusing a node; converting to JSON expands every alias into a full copy of the referenced value and discards the anchor mechanism. Don't rely on a JSON round-trip to preserve either. Once your data is structured, you might generate matching TypeScript interfaces from the JSON output.

Examples

Deployment config to JSON

name: billing-api
replicas: 3
regions:
  - us-east
  - eu-west
resources:
  cpu: 500m
  memory: 512Mi

A list and a nested map become a JSON array and object; scalars keep their inferred types (replicas is a number, cpu is a string).

Quote the Norway code

countries:
  - "NO"
  - SE
  - "ON"

NO and ON are quoted so they stay strings; leave them bare and a YAML 1.1 parser would coerce them to false and true.

Anchors expand to copies

defaults: &base
  retries: 3
  timeout: 30
prod:
  <<: *base
  timeout: 60

The *base alias is inlined during conversion, so the JSON output contains the merged values with no anchor reference left.

Frequently asked questions

Is JSON valid YAML?

Mostly yes. Since the YAML 1.2 spec, JSON is (almost) a strict subset of YAML, so pasting JSON into the YAML input usually parses and round-trips cleanly. The reverse does not hold: YAML has comments, anchors, and block scalars that JSON cannot represent.

Why did the value NO turn into false?

That is the 'Norway problem.' Under YAML 1.1-style boolean rules, bare words like no, yes, on, and off parse as booleans, so a country code NO becomes false. Quote ambiguous scalars ('NO', 'on', '1.20') to force them to stay strings.

Why won't my YAML parse?

The most common cause is a stray tab character. YAML indentation is significant and the spec forbids tabs for indentation, so a tab pasted in from an editor breaks the document even when it looks correctly aligned. Replace tabs with spaces.

Are comments and anchors kept when converting to JSON?

No. JSON has no comment syntax, so # comments are dropped, and YAML anchors and aliases (&name / *name) are expanded into full copies of the referenced value. Converting YAML to JSON is lossy by design.

Is my data sent to a server?

No. Parsing and serialization run entirely in your browser, so configs containing secrets, hostnames, or tokens never leave your machine and the tool works offline after the page loads.

How to use YAML ⇄ JSON Converter